TABLE 5.
Diagnostic accuracy of the iNtRON PCR kit, using a ≥4-fold rise in IFA antibody titers or an IFA IgM/IgG cutoff value of ≥1:1,024 as a gold standarda
| Rising IFA antibody titer or IFA IgM/IgG cutoff value of ≥1,024 |
Rising IFA antibody titer alone |
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Total |
Before antibiotic |
After antibiotic |
Total |
Before antibiotic |
After antibiotic |
|||||||
| Parameter | Case | Control | Case | Control | Case | Control | Case | Control | Case | Control | Case | Control |
| No. of iNtRON kit results: | ||||||||||||
| Positive | 70 | 0 | 49 | 0 | 17 | 0 | 60 | 0 | 43 | 0 | 13 | 0 |
| Negative | 18 | 51 | 9 | 17 | 9 | 1 | 9 | 44 | 6 | 16 | 3 | 1 |
| Total | 88 | 51 | 58 | 17 | 26 | 1 | 69 | 44 | 48 | 16 | 16 | 1 |
| Sensitivity, % (95% CI) | 79.5 (69.3–87.1) | 84.5 (72.1–92.2) | 65.4 (44.4–82.1) | 87.0 (76.2–93.5) | 87.8 (74.5–94.9) | 81.3 (53.7–95.0) | ||||||
| Specificity, % (95% CI) | 100 (91.3–100) | 100 (77.1–100) | 100 (5.5–100) | 100 (90.0–100) | 100 (75.9–100) | 100 (5.5–100) | ||||||
| PPV, % (95% CI) | 100 (93.5–100) | 100 (90.9–100) | 100 (77.1–100) | 100 (92.5–100) | 100 (89.8–100) | 100 (71.7–100) | ||||||
| NPV, % (95% CI) | 73.9 (61.7–83.4) | 65.4 (44.4–82.1) | 10.0 (0.5–45.9) | 83.0 (69.7–91.5) | 72.7 (49.6–88.4) | 25 (1.3–78.1) | ||||||
a
IFA, indirect immunofluorescence assay; 95% CI, 95% confidence interval; PPV, positive predictive value; NPV, negative predictive value.